package com.example.demo;

import org.apache.commons.codec.binary.Base64;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

@Component
public class RSAEncrypt {
  @Value("${rms.rsa.publicKey.key}")
  private String publicKey;

  @Value("${rms.rsa.privateKey.key}")
  private String privateKey;

  private static Map keyMap = new HashMap(); // 用于封装随机产生的公钥与私钥

  public static void main(String[] args) throws Exception {
    // 生成公钥和私钥

    genKeyPair();

    // 加密字符串

    String message = "df723820";

    System.out.println("随机生成的公钥为:" + keyMap.get(0));

    System.out.println("随机生成的私钥为:" + keyMap.get(1));

    // String messageEn = encrypt(message,keyMap.get(0));

    // System.out.println(message + "t加密后的字符串为:" + messageEn);

    // String messageDe = decrypt(messageEn,keyMap.get(1));

    // System.out.println("还原后的字符串为:" + messageDe);

  }

  /**
   * 随机生成密钥对
   *
   * @throws NoSuchAlgorithmException
   */
  public static void genKeyPair() throws NoSuchAlgorithmException {
    // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象

    KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");

    // 初始化密钥对生成器，密钥大小为96-1024位

    keyPairGen.initialize(1024, new SecureRandom());

    // 生成一个密钥对，保存在keyPair中

    KeyPair keyPair = keyPairGen.generateKeyPair();

    RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); // 得到私钥

    RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); // 得到公钥

    String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));

    // 得到私钥字符串

    String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));

    // 将公钥和私钥保存到Map

    keyMap.put(0, publicKeyString); // 0表示公钥

    keyMap.put(1, privateKeyString); // 1表示私钥
  }

  /**
   * RSA公钥加密
   *
   * @param str
   *     <p>加密字符串
   *     <p>公钥
   * @return 密文
   * @throws Exception
   *     <p>加密过程中的异常信息
   */
  public String encrypt(String str) throws Exception {
    // base64编码的公钥

    byte[] decoded = Base64.decodeBase64(publicKey);

    RSAPublicKey pubKey =
        (RSAPublicKey)
            KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));

    // RSA加密

    Cipher cipher = Cipher.getInstance("RSA");

    cipher.init(Cipher.ENCRYPT_MODE, pubKey);

    String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));

    return outStr;
  }

  /**
   * RSA私钥解密
   *
   * @param str
   *     <p>加密字符串
   *     <p>私钥
   * @return 铭文
   * @throws Exception
   *     <p>解密过程中的异常信息
   */
  public String decrypt(String str) throws Exception {
    // 64位解码加密后的字符串

    byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));

    // base64编码的私钥

    byte[] decoded = Base64.decodeBase64(privateKey);

    RSAPrivateKey priKey =
        (RSAPrivateKey)
            KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));

    // RSA解密

    Cipher cipher = Cipher.getInstance("RSA");

    cipher.init(Cipher.DECRYPT_MODE, priKey);

    String outStr = new String(cipher.doFinal(inputByte));

    return outStr;
  }
}
